Motor vehicle

ABSTRACT

A motor vehicle wherein the power train comprises an automated clutch between the engine and a manually shiftable transmission. The control circuit for the clutch is designed in such a way that the clutch is disengaged in response to actuation of the gear shifting lever simultaneously with one or more additional undertakings such as actuation of the gas pedal and of one or more brakes, a reduction of the speed of the vehicle below a preselected value, and/or many others.

BACKGROUND OF THE INVENTION

The invention relates to a motor vehicle with a driving unit, such asfor example a motor or a combustion engine, a transmission and anautomated torque transmitting system such as for example a clutch, afriction clutch or a magnetic powder clutch, the transmission ratiobeing selectable by a servicing element such as for example a shiftinglever, a sensor arrangement detecting the actuation of the servicingelement and a control unit being adapted to generate a control signal inresponse to which the torque transmitting system is disengaged in theevent of an actuation of the servicing element.

It is known from DE 17 55 528 that, in such motor vehicles withautomated torque transmitting systems, a shifting operation by actuationof the servicing element is possible only when the throttle valve is notactuated.

In technical systems, such as in the aforediscussed motor vehicles, evenminor irregularities or defects can grow to proportions which arecritical from the standpoint of operability of safety and which cannotbe accepted for reasons of operability or safety.

In a motor vehicle which embodies an automated torque transmittingsystem which permits a shifting of the transmission only when the gaspedal is not actuated, i.e., in the event of actuation of an idlingswitch which detects whether or not the gas pedal assumes its idleposition, a situation which is critical from the operational or safetystandpoint can arise, for example, in the event of the development of adefect in the region of connection between the gas pedal and the engine,for example in that the gas pedal jams and such defect does not permit aresetting of the gas pedal and actuation of the idling switch even whenthe gas pedal is not actuated. Under such circumstances, the automatedtorque transmitting system assumes, based on the then available sensorvalues, that the gas pedal is being actuated on purpose, for example bythe driver, and a shifting of the transmission or transmission gears isdifficult to accomplish due to the absence of disengagement of thetorque transmitting system.

In a motor vehicle with an automated torque transmitting system, it isnecessary that an actuation of the servicing element, such as forexample a gear shifting lever, can lead to a disengagement of the torquetransmitting system when it appears likely, on the basis of sensorsignals that were evaluated by the control unit, that such actuation isindeed desired by the driver. However, a disengagement of the torquetransmitting system should not take place in each and every case to thusensure that an unintended interruption of acceleration of the vehiclewill not occur when a shifting operation is not desired, for example, athigh rotational speeds of the engine and merely as a consequence of theplacing of a hand onto the servicing element. In accordance with DE 1755 528, this is accomplished in that a disengagement of the torquetransmitting system takes place only at a minimal position of thethrottle valve.

OBJECTS OF THE INVENTION

An object of the present invention is provide a vehicle which comprisesan automated torque transmitting system and renders it possible toreliably and effectively shift into various transmission gears basicallyunder all relevant operational circumstances.

Furthermore, it is an object of the present invention to provide a motorvehicle of the above outlined character which is designed in such a waythat, even in the event of the development of problems or defects in theregion of the gas pedal system, it is still possible to shift from orinto a desired transmission gear.

Furthermore, it is an object of the invention to improve motor vehiclesof the above outlined character. Furthermore, it is an object of theinvention to enhance the operativeness of the above outlined motorvehicles and to provide vehicles which, under circumstances, even permitthe achievement of a reduction of cost.

In accordance with the invention, such solution is accomplished in thatone generates a control signal when a load lever, such as a gas pedal,and a brake are actuated simultaneously while the servicing element isbeing actuated.

It can be of advantage if the brake is a vehicle brake or a parkingbrake, such as for example a manually operated brake.

Furthermore, it can be desirable that, among other situations, thecontrol signal be generated also when a load lever and a vehicle brakeand a parking brake are actuated simultaneously while the servicingelement is being actuated.

Furthermore, the object of the invention can be accomplished in that acontrol signal is generated when the servicing element is actuated whilethe speed of the vehicle is less than a preselectable limit value.

It is of advantage if the preselectable limit value is within a range of0 to 50 km/h, preferably of 0 to 30 km/h, and especially of 0 to 10km/h.

Furthermore, it can be of advantage if, in a motor vehicle with adriving unit and a transmission and an automated torque transmittingsystem, the transmission ratio being selectable by means of a servicingelement such as for example a gear shifting lever, a sensor arrangementdetecting the actuation of the servicing element and a control unitbeing adapted to generate a control signal in response to which thetorque transmitting system is disengaged in the event of actuation ofthe servicing element, the control signal be generated and the torquetransmitting system be disengaged in the event of actuation of theservicing element and in response to fulfillment of at least one of thefollowing prerequisites:

the idling switch is actuated,

the load is smaller than a preselectable limit value,

the throttle valve angle is smaller than a preselectable limit value,

the vehicle brake is actuated,

the parking brake is actuated,

a sensor indicates that a vehicle door is open,

the speed of the vehicle is less than a preselectable limit value,

the engine torque is smaller than a preselectable limit value,

the engine RPM is smaller than a preselectable limit value,

the value of the gradient of the engine torque in the event of anegative gradient exceeds a preselectable limit value,

the value of the gradient of the engine RPM in the event of a negativegradient exceeds a preselectable limit value,

the value of the gradient of the vehicle speed in the event of anegative gradient exceeds a preselectable limit value.

The individual preprequisites can be linked by AND or OR-connections.

For example, the disengagement of the torque transmitting system takesplace also when the engine torque which has been ascertained by thecontrol unit is above a preselected limit value but the nature of theother signals is such that they can be interpreted as denoting a desireby the driver to shift the transmission into a different gear.

Furthermore, it might be desirable that an intention to shift be foundto be permissible if

the engine torque exceeds a preselectable limit value,

the engine RPM exceeds a preselectable limit value,

the value of the gradient of the engine torque at a positive gradient isless than a preselectable limit value,

the value of the gradient of the engine RPM at a positive gradient isless than a preselectable limit value and/or

the value of the gradient of the vehicle speed at a positive gradient isless than a preselectable limit value,

and if such prerequisites are satisfied alone or in combination withother prerequisities in order to reach the conclusion that an intentionto shift actually exists.

Furthermore, it can be of advantage if, in a motor vehicle with adriving unit, a transmission and an automated torque transmittingsystem, the transmission ratio being selectable by means of a servicingelement such as for example a gear shifting lever, a sensor arrangementdetecting the actuation of the servicing element and a control unitbeing adapted to generate a control signal in response to which thetorque transmitting system is disengaged in the event of actuation ofthe servicing element, the control signal be generated and the torquetransmitting system be disengaged in response to actuation of theservicing element and after elapse of a waiting time Δt, provided thatthe servicing element continues to be actuated after the elapse of suchwaiting time and in response to fulfillment of a least one of thefollowing prerequisites:

the idling switch is actuated,

the load lever is smaller than a preselectable limit value,

the throttle valve angle is smaller than a preselectable limit value,

the vehicle brake is actuated,

the parking brake is actuated,

a sensor indicates that a vehicle door is open,

the vehicle speed is less than a preselectable limit value,

the engine torque is smaller than a preselectable limit value,

the engine RPM is smaller than a preselectable limit value,

the value of the gradient of the engine torque in the event of anegative gradient exceeds a preselectable limit value,

the value of the gradient of the engine RPM in the event of a negativegradient exceeds a preselectable limit value,

the value of the gradient of the engine speed in the event of a negativegradient exceeds a preselectable limit value.

The aforementioned waiting time can be within the time range of 0.1second to 10 seconds, preferably within the time range of 0.5 second to5 seconds.

Furthermore, in can be advisable in accordance with a novel concept ifthe gear shifting gate will be/is divided into at least two regions inwhich different limit values are utilised for detection of a shiftingintention. This means that, for example, higher shifting lever speedsare required in one region than in another region in order that thecontrol unit reach a conclusion that there actually exists an intentionto shift into a different gear.

It can also be of advantage if the limit values which are utilised for adetermination of an intention to shift be varied for example as afunction of time.

Furthermore, such limit values or threshold values can also be varied asa function of other operational parameters, for example, as a functionof the engine RPM.

It can be of advantage if, on reaching or exceeding of the limit values,such limit values be altered, such as raised or lowered, by the actualdata. Furthermore the changes can be altered, again, in dependency ontime.

In accordance with a further novel concept, it is of advantage if acontrol signal is generated also when, in addition, there is actuated aload lever, such as a gas pedal.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in greater detail with reference to theFigures. There are shown in:

FIG. 1 a schematic representation of a vehicle,

FIG. 2 a representation of a gear shifting gate,

FIG. 2a a detail of a gear shifting gate, and

FIG. 3 a diagram.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a vehicle 1 in a schematic representation with a drivingunit 2, a torque transmitting system 3 and a transmission 4. Thetransmission is followed by a drive shaft 5 and a differential 6 as wellas the driven axles 7a and 7b, the wheels 8a and 8b being driven by wayof the driven axles 7a and 7b. The vehicle can also be equipped with afour-wheel drive. However, this is not shown in FIG. 1.

The torque transmitting system 3, such as for example a friction clutch,a magnetic powder clutch or a torque converter with torque bypassclutch, is shown in FIG. 1 as in the power train between the engine 2and the transmission 4; however, it is also possible to install thetorque transmitting system 3 at the downstream side past thetransmission 4 in a manner which can be of advantage, for example, withinfinitely variable speed transmissions (CVT).

In the embodiment which is shown in FIG. 1, the torque transmittingsystem 3 comprises a clutch disc 3b with friction linings, a pressureplate 3c as well as a clutch cover 3d and a diaphragm spring 3e. Theseparts of the torque transmitting system can be mounted on a flywheel 3a,and they can also be assembled with the flywheel 3a as a preassemblableunit. Also, the flywheel can constitute a so-called twin-mass flywheelwhich comprises a torsional vibration damper between a primary and asecondary mass. The diaphragm spring 3e is acted upon by a disengagingbearing 3f to engage or disengage the clutch. By causing the disengagingbearing 3f to act upon the tongues of the diaphragm spring, the clutchcan be induced to assume a condition or can be adjusted in such a waythat it assumes a condition which is a fully engaged or a fullydisengaged condition or a condition between such extreme conditions. Inthis manner, the torque which can be transmitted by the torquetransmitting system 3 can be selected or fixed at will within the rangebetween zero and the maximum value.

In the embodiment of FIG. 1, the disengaging bearing is actuated by adisengaging lever 9, and this disengaging lever is actuated by ahydraulic system with a slave cylinder 10, a hydraulic conduit 11 and anactuator 12. The actuator 12 contains an adjusting device 12a which, ifa hydraulic system is employed, comprises a master cylinder and adriving unit for actuation of the master cylinder. The actuator 12further comprises an electronic arrangement 12b, such as a control unit,which processes signals being transmitted for example by sensorarrangements, sensors or other electronic units and generates controlsignals in order to operate the driving unit of the actuator for thepurpose of engaging or disengaging the torque transmitting system.

The transmission 4 is a transmission in which one can distinguishbetween various transmission ratios, such as gears, by means of aservicing element 13. In order to select a transmission ratio among aplurality of transmission ratios, the servicing element 13 is moved tothe corresponding position or is actuated in a manner and wise providedtherefor. Such actuation can be effected manually or automatically.

As already mentioned above, the arrangement for disengaging the torquetransmitting system can be operated by a pressurized-fluid system, andsuch pressurized-fluid system can constitute a hydraulic system, apneumatic system or another fluid-operated system. In such instances,the disengaging element can also constitute a central disengagingelement which is operated by a pressurised fluid. Further, the actuationcan be effected by mechanical means, such as for example a linkage.

A sensor arrangement 14 can be coupled to or provided on the servicingelement 13, and this sensor arrangement detects an actuation of theservicing element. The detection of an actuation can take place bymeasuring an acting force or by measuring a change of position or of achange of speed or acceleration. Furthermore, the actuation can bedetected in the event of exceeding a limit- or threshold value during amovement or actuation of the servicing element.

The sensor or the sensor arrangement 14 can be a travel- or velocity- oracceleration- or force-dependent sensor which detects or which candetect a movement of the servicing element or of an element which isconnected therewith or a force acting upon the servicing element or uponan element which is connected therewith.

Furthermore, it is possible to provide on the transmission 4 a sensor 15which detects the position of the shifted-in gear, for example, bysensing the position of shifting elements in the interior of thetransmission.

The sensors, such as the throttle valve sensor 16, the wheel RPM orvelocity sensor 17 (vehicle speed sensor), engine RPM sensor 18 andfurther sensors can be provided in/at the vehicle and connected with thecontrol unit by signal transmitting conductors. It is also possible toprovide on the vehicle a door sensor which detects whether a door isopen. It is also advisable to provide a sensor for detection of thethrottle valve angle. The control unit can also serve to calculate, fromthe data furnished by sensors, gradients which are utilized to evaluatethe intention to shift. For example, such gradients can be calculated byresorting to numerical procedures. Based on the sensor data and otherdata as well as system input values, the control unit 12 ascertains thecondition of the vehicle and generates a control signal for actuation ofthe torque transmitting system 3 in the event of conclusion that anintent to shift does exist.

If the driver actuates the servicing element of the transmission, thecontrol unit disengages the torque transmitting system by generating asignal to disengage the torque transmitting system. However, as a rule,this happens only when the calculated or ascertained engine torque issmaller than or equals a preselectable value of torque. Furthermore, anintention to shift can be rated as suppressed or as not establishedwhen, in addition to the determined engine torque, the position of thethrottle valve or the position of the load lever also exceeds a limitvalue.

The motor vehicle 1 further comprises a gas pedal 20, such as a loadlever, as well as an actuating element of a brake 21, such as a vehiclebrake, as well as an actuating element 22 for a brake, such as a parkingbrake. At the load lever 20, there is disposed at least one sensor 23which ascertains not only the extent of displacement a but also thepresence or absence of an actuation. A sensor which can determinewhether the pedal brake or the load lever is or is not actuated canconstitute an idling switch which is on when the pedal is not actuatedand which is off when the pedal is actuated.

At the actuating element 21 for the vehicle brake, such as a brakepedal, there can be provided a brake switch 24 which detects whether thebrake is actuated. Such a brake switch can also be provided at theactuating element 22 for the parking brake, and the sensor 25 detectswhether the parking brake is actuated.

Furthermore, the sensoric arrangement 23 for the load lever 20 can be insignal transmitting connection with the engine electronics 30 so that,in response to actuation of the gas pedal, the engine electronics 30regulate the engine RPM and the engine torque accordingly.

Based on the signals, such as measurement data and system input values,which are being transmitted to the control unit 12, it is possible toascertain the then transmitted engine torque.

The transmitted engine torque is the actual engine torque minus/plus thetorques which are taken up or transmitted by the auxiliary aggregates.For example, an air conditioning system or an inertia flywheel can betermed an auxiliary aggregate. Furthermore, it is possible to take intoconsideration drag torques.

Furthermore, it is possible to ascertain whether the servicing element13 is being actuated, whether a brake 21, 22 is being actuated andwhether the gas pedal, such as load lever, is being actuated. Thecontrol unit 12 recognises an intention to shift on the basis ofactuation of the servicing element 13 in response to signals which arebeing transmitted by the sensor 14 and/or 15. Whether an intent to shiftis evaluated or accepted by the control unit as a desire to shift andresults in the generation of a control signal to disengage the clutchdepends upon the system parameters.

For example, it is not invariably desirable that a shifting intentiondenoting signal be invariably interpreted as denoting an imminent gearshifting operation. As a rule, it is assumed--as a prerequisite for adesired gear change or for shifting out of a particular gear--that theengine torque be below a preselectable limit value and/or that theextent of actuation of the load lever be less than a preselectable limitvalue. This means, for example, that the load lever is not actuated andthat this is being indicated by the idling switch. However, such aprerequisite does not suffice under certain circumstances which arecritical for proper operation or adequate safety.

Furthermore, such prerequisites can be interlinked in such a way thatnot only is the engine torque below a preselectable limit value but theextent of actuation of the load lever is also below a preselectablelimit value. Furthermore, it can be of advantage that, under certaindriving conditions, while exceeding at least one of the aforementionedlimit values an intention to shift is interpreted as existingnevertheless and the control unit generates a control signal so that thetorque transmitting system is disengaged. For example, such controlsignal can be generated if, for example, an actuation of the servicingelement for the purpose of gear shifting takes place simultaneously withthe actuation of the load lever and e.g., one of the brakes.Furthermore, it can be of advantage if, at a vehicle speed which is lessthan a comparable reference speed, the control signal to disengage thetorque transmitting system is generated during actuation of theservicing element.

Such acceptance of an intention to shift and the generation of a controlsignal at low vehicle speeds might be desirable in the event of adisturbance, for example, of the gas pedal, e.g., as a result of jammingor another faulty operation, in order to shift from a particular gear.This is particularly desirable while the vehicle is being driven at lowspeeds, such as for example within the velocity range of between 0 and50 km/h, preferably of 0-30 km/h or of 0-10/20 km/h.

A further regulating method which can be of advantage in the event ofthe aforementioned operating conditions or faulty operations of the gaspedal system or in the vehicle can be that simultaneous actuation of abrake and of the gas pedal allows for acceptance of an intention toshift whereupon the control unit generates a control signal in order todisengage the torque transmitting system.

In addition to the brake or brakes, it is also possible to employadditional signals which, for example, must be present simultaneouslywith that from the gas pedal in order to accept an intention to shift inresponse to an actuation of the servicing element and to generate acontrol signal which disengages the torque transmitting system.

If the gas pedal system is operative, it is advisable that the controlunit ascertain an intention to shift on the basis of incoming signals,and such intention is examined prior to generation of a control signalfor the purpose of disengaging the torque transmitting system. When thebrake is not applied or when the vehicle speed is high, it might beadvisable that the control unit evaluate a shifting intention signal asnon-existent in spite of actuation of the servicing element when theengine torque exceeds a certain limit value. This should prevent faultydisengagements because one can assume that the driver would be unlikelyto shift when the engine torque is high. However, if a reduction of theengine torque has taken place, one can assume that the driver would liketo shift and, under such circumstances, it is desirable that theintention to shift be interpreted as such and entails the generation ofa control signal in order to disengage the torque transmitting system.

However, even following a cold start, the engine might be capable offurnishing--for example as a result of ignition shift or cold startenrichment or in accordance with other methods--during idling a torquewhich is above the limit torque and prevents that an intention to shiftbe evaluated as such and that it entail the generation of a controlsignal for disengagement of the clutch. Therefore, it might be advisableas a rule or under such operating conditions to also monitor the idlingswitch in addition to a comparison of the actual engine torque with alimit value. If the idling switch is actuated, i.e., if the throttlevalve value is below a limit value, the intention to shift isinterpreted as such and there is generated a control signal whichentails a disengagement of the torque transmitting system. Thus, anintention to shift is always possible during idling, namely when theidling switch is actuated, and a shifting operation is rendered possiblein that the torque transmitting system is disengaged in response toactuation of the servicing element.

If, based on the input signals such as sensor values and other signals,the control unit 12 detects an intention to shift, such intention isfirst tested prior to disengagement of the clutch. Under customarycircumstances of operation of the vehicle, it is advisable that theintention to shift be disregarded by the control unit when the enginetorque exceeds a predetermined limit value. Such predetermined torque,minus for example the drag torques and torques attributable to auxiliaryconsumers, is compared by the control unit with a reference value and,when the engine torque exceeds the limit value, an intention to shift isinterpreted as non-acceptable and the torque transmitting system is notdisengaged. This should prevent faulty disengagement because one canassume that the driver would not wish to shift while he demands a torque(output). However, it is also conceivable to resort to other mechanismswhich prevent an intention to shift under certain circumstances, forexample, a time delay during forwarding of the intention to shift. Thismeans that, in spite of a high engine torque, an intention to shiftwhich is indicated upon actuation of the servicing element will beaccepted after elapse of a waiting time Δt provided that an actuation ofthe servicing element is still present after elapse of the waiting time.Under such circumstances, the torque transmitting system is disengagedin spite of the existence of a high engine torque.

The aforementioned waiting times can be within a time span of 0.1 secondto 10 seconds, preferably within a time span of 0.5 second to 5 seconds.

Following a cold start, the engine in its capacity as the driving unitof the vehicle can furnish during idling an engine torque which is abovethe preselectable limit value, for example, as a result of an ignitionshift and/or cold start enrichment or by resorting to other methods.This can entail, under certain circumstances, a rolling of the vehicleand, due to a cancellation of the intention to shift, it is not possibleor quite difficult to shift the transmission out of gear. Such situationcan become critical from the standpoint of safety if the shiftingintention is interpreted as not recognised and the torque transmittingsystem remains engaged. Furthermore, it can become critical if the gaspedal becomes stuck, for example, due to a defect while the engine isnot idling and, therefore, the intention to shift cannot be followed. Itcan also become critical, from the standpoint of safety, if theintention to shift is disregarded for other reasons.

A solution in accordance with the invention provides that the intentionto shift is always accepted as being in existence when the idling switchis actuated, namely when the gas pedal has reassumed its idling positionof rest. Furthermore, it might be advisable that, in addition to thosefurnished by the idling switch, other signals resp. their combinationsbe utilised in order to accept the shifting intention, i.e., todisengage the torque transmitting system in response to an actuation ofthe servicing element. It can be particularly desirable if the idlingswitch is actuated and/or the gas pedal value, namely the load pedalvalue is below a limit value. Analogously, it is possible to take intoconsideration also the signal denoting the angle of the throttle valveor other signals denoting that the driver demands an output, and suchsignals, too, should be below preselectable threshold values.Furthermore, it can be desirable to recognize or interpret a shiftingintention as valid when the vehicle brake is operated or when theparking brake is actuated. Furthermore, it is possible to address a doorcontact switch and to accept an intention to shift when a door is openand this is being indicated by the signal from the door contact switch.It is also possible to employ other signals which indicate that thedriver does not desire to set the vehicle in motion. For example, thiscan happen when a driver in the vehicle is not recognised, such as forexample by a seat sensor so that the shifting out of gear must becarried out by a driver's mate which, in such case, should be preventedby the control unit if at all possible.

It can also be desirable if an intention to shift is invariably acceptedat lower driving speeds, such as for example within the range of from 0to 10 km/h or 0 to 20 km/h or 0 to 50 km/h.

It can also be desirable if an intention to shift is accepted onactuation of the servicing element for the purpose of changing thetransmission ratio and the torque transmitting system is disengaged whenthe engine RPM is below a preselectable limit value, such as about 1400RPM or 2000 RPM.

Still further, it can be of advantage if the value of the gradient ofRPM and/or speed of the vehicle is above a preselectable value; in suchcase, the gradient should be a negative gradient.

For example, such a situation can arise when the driver would like tostop but is incapable of shifting out of gear.

It is further proposed that, in such cases and/or all other combinationsof characteristics, the shifting intention recognition be set to be moresensitive. For example, the shifting intention thresholds can be set tobe below those under other, namely typical, driving conditions. Suchmore sensitive setting of the recognition of the intention to shiftdenotes that the threshold values which are set as preselectablethreshold values are shifted nearer to the position of a non-actuatedsystem or nearer to the values of the non-actuated servicing element inorder to detect, on the basis of values of signals furnished by thesensors, whether or not the servicing element has been actuated.

A change of the thresholds of intention to shift or of preselectablelimit values which lead to the intention to shift can also be regulatedin dependency on time which means that an intention to shift takes placeafter a certain time delay. Different shifts in time can be defined fordifferent driving conditions.

Furthermore, it can be of advantage if the limit values arepreselectable under customary driving conditions. Under thosecircumstances of the operation of a vehicle when safety-relatedsituations might become relevant with a higher degree of probability, itis possible to carry out a staggered utilisation of limit values. Forexample, if an actuation of the servicing element takes place in asituation when the engine torque is higher, the intention to shift canbe suppressed upon exceeding of a first threshold value because it isassumed that a desire to shift does notexist. However, if the actuationcontinues and the servicing element is guided beyond a second thresholdvalue, one can assume that an intention to shift does exist and thetransmission of torque can be interrupted because one can assume thatthe driver of the vehicle knowingly actuates the servicing lever.Therefore, it is proposed to define for the threshold values a secondset of disengaging thresholds and to introduce such values for therecognition of an intention to shift. If the actuation of the servicingelement exceeds such second threshold as a result of actuation of theservicing element by the driver, an intention to shift can be presumedindependently of other signals and the torque transmitting system can bedisengaged in response to the generation of a control signal.

As already explained hereinbefore, a detection of an intention to shiftis carried out by at least one sensor which monitors the movement of aservicing element and/or the position of a servicing element and/or thespeed and/or the acceleration of a servicing element. Furthermore, sucha sensor can also detect the application of forces to the servicingelement, either directly or indirectly. By utilizing a distance sensorin the region of the servicing element and a movement sensor in theregion of shifting elements in the interior of the transmission, and ifone assumes the presence of elastic parts in the power flow between theservicing element and the internal shifting elements of thetransmission, it is possible to carry out a measurement of differencesbetween various distances in order to obtain a signal which isproportional to or representative of the forces and can be utilized foran evaluation of the intention to shift.

It is further possible to carry out, among others, a velocity-dependentrecognition of an intention to shift when the vehicle employs anautomated clutch system. If the velocity of the shifting lever (suchvelocity can be filtered or otherwise modified) exceeds a preselectablelimit value, an intention to shift may exist and can be initiated by thecontrol unit. The speed of the shifting lever can be evaluated indifferent ways in dependency upon the direction, for example in adirection toward the position in neutral gear or in the oppositedirection. If the transmission is shifted into a gear by hand, thedriver normally forces the gear shifting lever in a direction toward andbeyond the selected gear in order to ensure that the transmission isbeing shifted into the desired gear. As used herein, the term forcing orovershifting is intended to denote that the shifting lever, such as theaforementioned servicing element, is caused by the driver to move in adirection toward the selected gear beyond that position and/or with aforce greater than necessary for actual shifting into such gear. Suchovershifting entails an elastic prestressing of some or even all of theelements which participate in a gear shifting operation. When the driverthereupon releases the lever, the latter can relatively rapidly returnto the actual (non-exceeded) position of rest in the selected gear. Suchreturn movement or relaxation to the actual position in a selected gearcan take place at a speed which exceeds the preselectable limit speedfor recognition of an intent to shift. Such exceeding by the actualvelocity of the preselectable limit value can be detected andunintentionally interpreted as an intention to shift so that it actuallytriggers a shifting operation with short-lasting disengagement of theclutch. When the step of relaxation of the shifting lever is completed,the shifting lever is again at a standstill essentially in a positioncorresponding to the idle condition of the gear shifting means and theintention to shift no longer exists.

Such short-lasting disengagement subsequent to release of the shiftinglever from its overshifted position furnishes an undesirableuncomfortable effect. The rebounding or relaxing of the shifting leverbasically takes place within a range which, in a direction towardneutral, is limited by the position of rest of the shifting lever whenthe transmission is in gear. As long as the shifting lever dwells withinsuch range, which might possibly be widened by a tolerance band, theintention to shift can be additionally scanned or rendered moredifficult or prevented in one or more following ways.

This range is a range of positions of the shifting lever starting fromthe position of rest in gear and in a direction away from the neutralposition.

FIG. 2 illustrates this situation in connection with a typical gearshifting gate for movements of a gear shifting lever in a change speedgear. The servicing element or shifting lever is moved along the severalshifting paths 100 to shift into and from gears, for example, from theneutral position along the selecting paths 101 to change its positionbetween the shifting paths 100. For example, in order to move theshifting lever from a neutral region into the first gear, the shiftinglever is guided, for example, from the point 102 to the point 103because the driver does not know exactly the position of rest in thefirst gear 104 and, as a rule, does not immediately advance the shiftinglever exactly to the optimum position for the first gear. When theshifting lever is released, it relaxes or eases into the gear restposition 104, i.e., the shifting lever moves from the point 103 to thepoint 104. In the course of such movement, the shifting lever can attaina speed which can exceed the preselectable limit value that is requiredto initiate a shifting intention. Therefore, and as concerns thethreshold values as well as the initiation of a shifting intention, theregion 105 is interpreted differently from the region 106 which latterextends from the rest position 104 for the particular gear in adirection toward neutral. On the other hand, the region 105 is directedfrom the gear rest position 104 and away from neutral.

In the selected region 105 which, in the region of the gear restposition, can overlap for example with the region 106 in a manner asshown in FIG. 2a, there can exist a changed or altered evaluation ofsignals for recognition of the intention to shift, as compared with anevaluation in the region 104 and/or 106. In the region 105 ofoverstressing, an intention to shift can invariably be interpreted asbeing undesirable.

Furthermore, it is possible to raise the preselectable limit values orrelease threshold in the region of overstressing, i.e., an initiation ofthe intention to shift in the region of overstressing must satisfyincreased requirements as concerns the changes pertaining to theservicing lever or shifting lever. Furthermore, it is possible to filterthe movement or velocity signals from the sensors, especially to resortto a more pronounced filtering action than in the normal region. In thiscontext, this is intended to express that the filtering operation iscarried out with an increased time constant which entails atime-dependent smoothing or also a delay of the effects. Still further,it is desirable to resort to the above enumerated methods only for alimited period of time and, once such period has expired, a recognitionof the intention to shift is carried out in accordance with methodswhich can also be resorted to in the region 106. As the start of theinterval of time Δt subsequent to which the recognition of an intentionto shift is again carried out in accordance with normal methods, one cantake into consideration the instant of recognition of a new gear whichhas been shifted into or the instant of reaching the position of rest inthe newly shifted into gear or the instant of the start of overstressingor exceeding of the position of rest in the particular gear or of theexceeding of an overstressing limit.

Furthermore, it can be of advantage if an intention to shift isconsidered as non-existent, so that a disengagement of the torquetransmitting system is prevented, only while the signal or signals fromsensor or sensors indicates or indicate an overstressing. For example,an overstressing can be detected by measuring the magnitude of the forceor by measuring the extent of stretching of the external circuitry,namely the connection between the shifting lever and the transmission.Still further, it is possible to resort to a combination of theaforementioned conditions.

The region of overstressing and the location of the shifting lever insuch a region of overstressing can be monitored by the existing sensors,or one employs additional sensors which can be designed, for example, asdigital or continuous, analog sensors and monitor the position of theshifting lever in the region of overstressing.

As described hereinbefore, the detection of an intention to shift on thebasis of a movement of a servicing element necessitates the division ofthe actuating movement of the servicing element into at least tworegions. Starting from the neutral position, one of the regions isselected to extend essentially to the position of rest in the selectedgear and the second region extends, starting essentially from theposition of rest, in a direction away from the neutral position. One canresort to different evaluations of sensor signals, of the movement,position, speed, acceleration or force of the servicing element or uponthe servicing element, depending upon whether the servicing element islocated in the one or the other region. It is preferred to carry out anincrease of the preselectable limit values in that one region which isthe region of overstressing in order to avoid a shifting intention as aresult of a relaxation of the shifting lever upon completion of a gearshifting operation.

When the clutch is an automated clutch, the basic purpose of detectionof the intention to shift is to ascertain the desire of the driver asfar as shifting is concerned. If a desire to shift is detected on thebasis of sensor signals which are being transmitted to the control unitand an appropriate evaluation of such signals, the clutch is normallydisengaged in order to ensure that shifting out of a gear is madepossible in response to the exertion of a relatively small force by thedriver of the vehicle. In many instances, the intention to shift isdetected in such a way that one or more sensor signals, which might havealready undergone a preliminary treatment, such as filtering, exceed afixed or a variable preselectable threshold. This can readily entail aback and forth shifting of the intention to shift if the sensor signalalternately execeeds and falls below the preselectable threshold, i.e.,if the intensity of the signal fluctuates. For example, such a situationcan arise if the intention to shift is recognized on the basis of fixeddistance thresholds and the position of the manually shiftable leverexceeds such thresholds. If the driver maintains the shifting lever onthe border of distance thresholds, for example, by placing his hand inthe region of the shifting lever, or shifts very slowly, even slightvehicle- or driver movements, such as oscillations, can entail repeatedexceeding and falling below the threshold values. Even a disengagementof the clutch can entail an acceleration of the vehicle which caninfluence the shifting lever through the driver or through the vehicle.In the event that the intention to shift is detected as a result offorce measurement at the shifting lever, or at another location betweenthe transmission and the shifting lever, it is also possible that theredevelops a back and forth oscillation or an exceeding or falling belowthe threshold values. An intention to shift is initiated when theactuating force exceeds a certain limit value. This, too, can result inoscillations, i.e., in exceeding of or in falling below the thresholdvalue as a consequence of intentional or unintentional retention at therelease threshold. Such effect is enhanced in that the clutch becomesdisengaged in the event of an intention to shift. This causes thetransmission to furnish no output or a lesser output and the shiftingforce can be reduced. This entails a decrease of the actuating force andthe release threshold is not reached. A similar effect can develop alsoin the event of a measurement of differences between distances whichinvolves distance measurements at two locations in the region betweenthe shifting lever and the shifting elements for the transmission, itbeing assumed that elastic parts are disposed between the two locations.Under such circumstances, it might be of advantage if the preselectablelimit values, which must be exceeded in order to initiate an intentionto shift are provided with a hysteresis which means that, if thepreselectable limit value is exceeded, the limit value is reduced by anamount ΔGrenz. In other words, the signal must exceed the threshold. Assoon as the signal has exceeded the threshold of the intention to shift,or has exceeded the limit value, the threshold is caused to be loweredby a certain amount. The intention to shift is withdrawn and thethreshold or the limit value is increased again only when the signalagain drops below the lowered threshold or the lowered limit value. Theamount ΔGrenz of lowering can be variable or a function of time. Thevalue ΔGrenz can be selected in different ways and can even rise or fallthereafter as a function of thine in dependency on the operating point,such as for example the selected gear, the engine RPM or the position ofthe throttle valve. Alternatively, it is also possible to manipulate,namely increase, the signal value. The extent of lowering and subsequentincrease can even begin as a function of time and can also be withdrawnas a function of time. Such situation is illustrated in FIG. 3 wherein asignal, for example that from a sensor, for detection of an intention toshift is represented as a function of time. For example, the signal candenote the position of the servicing element, such as a shifting lever,and is detected as a function of time.

From the instant t₀ to the instant t₁, the signal 200 is below thepreselectable limit value for the initiation of an intention to shift.At the instant t₁, the signal 200 exceeds the threshold of the intentionto shift at which time the threshold of the intention to shift isimmediately lowered from the value 201 to the value 202. The signal 200varies during the interval between t₁ and t₂ but it reaches thethreshold 202 only at the instant t₂ so that, from the instant t₂, theintention to shift is interpreted as having been withdrawn.Simultaneously, namely at the instant t₂, the threshold of the intentionto shift or the preselectable limit value for the initiation of anintention to shift is reset to the value 201. It is also possible toprovide a time-dependent threshold 203 as an alternative of the fixedthreshold 202.

If an intention-to-shift signal is present, i.e., the servicing elementis being actuated and, for example, the engine torque is below apreselectable threshold value, the control unit generates a controlsignal so that the torque transmitting system is disengaged. Thedisengagement of the torque transmitting system can take place asexpeditiously as possible or at a variable speed in dependency upon theshifting operation. For example, based on the incoming signals thecontrol unit can ascertain and recognise the driving condition of thevehicle and, based on the information pertaining to the operatingcondition, the clutch can be engaged at a lower or at a higher speedwhen an intention to shift does exist. This can be of advantage in orderto weaken or avoid impacts on disengagement of the clutch. If, uponrecognition of an intention to shift, the shifting velocity (namely thespeed of movement of the servicing element) is below a preselectablethreshold and at the same time, for example, the engine torque is belowa preselectable threshold and/or the speed of the vehicle is below apreselectable threshold, the clutch is disengaged at a slower rate butat a predetermined speed, for example, at 30 Nm per second.

As a rule, a normal shifting operation takes up an interval in the rangeof between 0.1 second and 0.5 second. Thus, a slow shifting operationcan stretch out for an interval of for example 0.4 second to 2 secondsor even longer. The lower limit for such a slow shifting operation fromone shifted-into gear to another shifted-into gear can depend, however,upon the vehicle and the transmission which is being utilized in thevehicle. The shifting operation can be identified as a slow shiftingoperation if, upon selection of a fixable distance, a preselectableinterval of time or a limit value for a preselectable duration of a slowshifting operation is already exceeded in the course of a shiftingmovement but the limit for the preselectable distance is not exceeded.Furthermore, the next step can involve an actuation of the torquetransmitting system in accordance with the prerequisites for a slow gearshifting operation, for example, a slow disengagement of the torquetransmitting system.

For example, the normal speed of opening the actor can be in the rangeof between 1 to 5000 Nm per second. During that stage of operation ofthe vehicle when the vehicle is creeping, such creeping being effectedas a result of transmission of a small torque, for example, 10-20 Nm, itmight be advisable to disengage the clutch slowly in the event of anintention to shift. If the clutch is disengaged at a speed of 30 Nm persecond, and if the transmissible creeping torque is in the range of 15Nm, the clutch can be readily disengaged within an interval of one-halfof one second. The speed of disengagement of the torque transmittingsystem can be calculated or determined in dependency upon the operatingcondition and can be selected differently in dependency upon the drivingconditions and the shifting situation.

The full range of velocities of the actor for the torque transmittingsystem is available for the selection of the speed of disengagement.

As described hereinabove, the shifting intention signal is a digitalsignal which means that there exists an intention to shift, or it isclassified as non-existent, or it does not exist. Furthermore, it ispossible to determine or calculate and process the shifting intentionsignal as a continuous signal. The clutch torque can be reduced evenprior to exceeding of a release threshold or of a preselectable limitvalue for the initiation of an intention to shift. The transistion from"slow disengagement" of the torque transmitting system to "rapidinterruption" of the torque transmitting system would then constitute acontinuous transition, depending on the nature of actuation of theservicing element by the driver. A continuous transition would alsoexist for the duration of actual disengagement in the event of a gearshifting operation. Under such operating circumstances, there candevelop a short-lasting phase of slip prior to disengagement of thetorque transmitting system while the power train is not under stress sothat one can in this manner counteract the buildup of a vibration at theinput side of the transmission. This means that an at least slightdisengagement of the torque transmitting system is already initiated inresponse to detected movement of the servicing element even though thepreselectable threshold value for the recognition of an intention toshift has not been exceeded as yet. The extent of such at least slightdisengagement can be selected in dependency upon the filtered orprocessed signal values but the typical vibrations of the shifting levershould not be considered.

What is claimed is:
 1. In a motor vehicle, a combination comprising:adriving unit; a transmission having a variable transmission ratio; meansfor selecting said transmission ratio, including an actuatable servicingelement; an automated engageable and disengageable torque transmittingsystem; an actuatable load lever; actuatable brake means; a signaltransmitting sensor arrangement including means for monitoring thecondition of said servicing element, said load lever and said brakemeans; and a control unit arranged to receive signals from said sensorarrangement and to generate a control signal, in response to which saidtorque transmitting system is disengaged, when said servicing element isactuated simultaneously with said load lever and said brake means. 2.The structure of claim 1, wherein said torque transmitting systemcomprises a clutch.
 3. The structure of claim 1, wherein said shiftingelement comprises a gear shifting member.
 4. The structure of claim 1,wherein said load lever includes a gas pedal.
 5. The structure of claim1, wherein said brake means comprises at least one of a vehicle brakeand a parking brake.
 6. The structure of claim 1, wherein said brakemeans comprises an actuatable vehicle brake and an actuatable parkingbrake, said control unit being arranged to generate a control signalwhen said servicing element is actuated simultaneously with said loadlever, said vehicle brake and said parking brake.
 7. The structure ofclaim 1, wherein said transmission has a gear shifting gate including atleast two sections in which different limit values are required for theascertainment of a shifting intention.
 8. The structure of claim 1,wherein said transmission has a gear shifting gate and the limit valueswhich are utilized for a determination of a shifting intention vary as afunction of time.
 9. The structure of claim 1, wherein said transmissionhas a gear shifting gate and the values which are utilized or adetermination of a shifting intention are altered upon reaching orexceeding of limit values.
 10. The structure of claim 9, wherein saidvalues are raised upon reaching or exceeding of limit values.
 11. Thestructure of claim 9, wherein said values are lowered upon reaching orexceeding of limit values.
 12. In a variable-speed motor vehicle, acombination comprising:a driving unit; a transmission having a variabletransmission ratio; means for selecting said transmission ratio,including an actuatable servicing element; an automated engageable anddisengageable torque transmitting system; a signal transmitting sensorarrangement including means for monitoring the condition of saidservicing element and the speed of the motor vehicle; and a control unitarranged to receive signals from said sensor arrangement and to generatea control signal, in response to which said torque transmitting systemis disengaged, when the speed of the motor vehicle is below apreselectable value in response to actuation of said servicing element.13. The structure of claim 12, wherein said torque transmitting systemincludes a clutch.
 14. The structure of claim 12, wherein said servicingelement comprises a gear shifting member.
 15. The structure of claim 12,wherein said preselectable value is between about 0 and 50 kilometersper hour.
 16. The structure of claim 12, wherein said preselectablevalue is between about 0 and 30 kilometers per hour.
 17. she structureof claim 12, wherein said preselectable value is between about 0 and 10kilometers per hour.
 18. The structure of claim 12, further comprising aload lever actuatable to influence the operation of said driving unit,said control unit being further arranged to generate said control signalin response to actuation of said load lever.
 19. In a variable-speedmotor vehicle, a combination comprising:a variable torque-transmitting,variable-RPM engine; actuatable vehicle and parking brakes; a doorhaving open and closed positions; a pivotable throttle valve; atransmission having a variable transmission ratio; means for selectingsaid transmission ratio, including an actuatable servicing element; anactuatable idling switch; an automated engageable and disengageabletorque transmitting system; a load lever actuatable to a variableextent; a signal transmitting sensor arrangement including means formonitoring the condition of said servicing element, said load lever,said brakes, said idling switch and said load lever, the position ofsaid door, the speed of the vehicle, the engine torque, the extent ofpivoting of said throttle valve, and the engine RPM; and a control unitarranged to receive signals from said sensor arrangement and to generatea control signal, in response to which said torque transmitting systemis disengaged, when said servicing element is actuated and in responseto the fulfillment of at least one of the following prerequisites:saididling switch is actuated, said load lever is actuated to less than apredetermined extent, said throttle valve is pivoted to less than apredetermined extent, at least one of said brakes is actuated, said dooris open, the speed of the motor vehicle is below a predetermined value,the value of the gradient of engine torque, in the event of a negativegradient, exceeds a preselectable limit value, the value of the gradientof the engine RPM, in the event of a negative gradient, exceeds apreselectable limit value, and the value of the gradient of the vehiclespeed, in the event of a negative gradient, exceeds a preselected limitvalue.
 20. In a variable-speed motor vehicle, a combination comprising:avarible torque-transmitting, variable-RPM engine; actuatable vehicle andparking brakes; a door having open and closed positions; a pivotablethrottle valve; a transmission having a variable transmission ratio;means for selecting said transmission ratio, including an actatableservicing element; an actuatable idling switch; an automated engageableand disengageable torque transmitting system; a load lever actuatable toa variable extent; a signal transmitting sensor arrangement includingmeans for monitoring the condition of said servicing element, said loadlever, said brakes, said idling switch and said load lever, thepoisition of said door, the speed of the vehicle, the engine torque, theextent of pivoting of said throttle valve, and the engine RPM; and acontrol unit arranged to receive signals from said sensor arrangementand to generate a control signal, in response to which said torquetransmitting system is disengaged, when said servicing element isactuated and after elapse of a predetermined interval of time, providedthat said servicing element remains actuated during and after the elapseof said interval and in response to fulfillment of at least one of thefollowing prerequisites:said idling switch is actuated, said load leveris actuated to less than a predetermined extent, said throttle valve ispivoted to less than a predetermined extent, at least one of said brakesis actuated, said door is open, the speed of the motor vehicle is belowa predetermined value, the value of the gradient of engine torque, inthe event of a negative gradient, exceeds a preselectable limit value,the value of the gradient of the engine RPM, in the event of a negativegradient, exceeds a preselectable limit value, and the value of thegradient of the vehicle speed, in the event of a negative gradient,exceeds a preselected limit value.